Furnace for the continuous annealing of bands, sheets, and wires



Jan. 2, 1940. E. VITS 2,185,655

FURNACE FOR THE CONTINUOUS ANNEALING 0F BANDS SHEETS; AND WIRES FiledDec. 14, 1956 lfiyewfor EM/L v/Ts Attorney.

Patented Jan. 2, 1940 rmmacr: roa

PATENT OFFICE THE CONTINUOUS ANNEAL- ING 0F BANDS, SHEETS, AND WIRESEmil Vita, Dusseldorf, Germany Application December 14, 1936, Serial No.115,858 In Germany January 18, 1936 This invention relates to a furnacefor annealing or hardening, in particular for bright annealing strips,sheets, wires and the like which are passed through the furnacecontinuously. The fundamental idea of the invention is to employ forannealing the work a furnace in which the direction of travel of thework or material to be annealed is reversed in the furnace, so that thework leaves the furnace from the same end at which it enters. Thefurnace is so constructed and the work is guided through the furnace insuch way that the work travelling in one direction does not come intocontact in the actual annealing chamber with that travelling in theopposite direction, so that all surfaces of the work are exposed to theheat radiated in the annealing chamber. At the entrance end of thefurnace, when bands for example are being annealed, the two parts of theband which travel one above the other are guided as closely together aspossible, so that the entering part of the band becomes heated as itenters the furnace by the part of the band which is leaving the furnaceand, at the same time, the said part of the band which i leaving thefurnace becomes cooled, in order to increase the mutual cooling andheating of the parts of the band entering and leaving the furnace. Themuiile which acts as the annealing chamber is preferably prolonged atthe inlet end of the furnace so that the work becomes preheated to someextent before it enters the actual annealing chamber. By this means, thework leaving the furnace can be simultaneously cooled down to such anextent that it is only just warm. A device for changing the direction oftravel of the work is disposed in the annealing chamber at the closedend of the furnace remote from the entry end, which device preferablyconsists of one or more rollers which may be driven. The rollers aremade of heat resistant material and provision should be made to ensurethat they do not scratch the work. The rollers can, if necessary, beprovided with guides for the work which passes round them. The openingfor entry of the work into the furnace and through which the worktravelling in the reverse direction also leaves the furnace is sodesigned that the annealing chamber can be closed as nearly airtightlyas possible. In order to prevent access of air to the annealing chamber,a protective gas at a pressure higher than atmospheric pressure isconducted into and maintained in the annealing chamber. Then some ofsuch gas will always escape into the atmosphere through the (CL 28H)inlet opening and thereby prevent the entry 0 external air into theannealing chamber. The consumption of the protective gas employed isonly trifling. The furnace can be heated in known manner by gas or othersources of heat such as electric current, 011, coal and the like. Thedevices for unwinding and winding the work are arranged at the entranceend of the furnace and provided with suitable driving means.

Since in the new furnace the work to be annealed changes its. directionof travel in the furnace the actual annealing chamber can beconsiderably shorter than in the known furnaces in which the work to beannealed is passed through the furnace in one direction only. Theconsumption of heat in the new furnace is also considerably less than inthe known furnaces.

Further, a number of sheets, bands or the like can be conducted onebeside another through the furnace. The reversing device is thenconstructed in such a manner as to ensure each strip being separatelyguided. The work which leaves the furnace is bright annealed.

A constructional embodiment of a furnace for annealing strip orband-like material is illustrated by way of example in the accompanyingdrawing, in which:

Figure 1 is a longitudinal section through the furnace.

Figure 2 is a section through the furnace on the line AB of Figure l,and

Figure 3 is a cross section on a larger'scale of the opening whichserves as the inlet to and outlet from the furnace.

Referring to the drawing, the annealing furnace consists of the furnacei having an annealing muille 2, the height of the actual annealingchamber 3 of which increases towards the completely closed hot end ofthe furnace. In the example illustrated the furnace is electricallyheated. The heating elements 4 are arranged closely together around theactual annealing chamber in order to produce the strongest heatingthere. There are fewer heating elements in the central zone 5 of thefurnace, while at the inlet end 6 there are none at all. In

'order to cool thevband as it leaves the furnace by the radiation ofheat from it, the muiiie 2 is prolonged beyond the inlet end of thefurnace I. At the end of the expanded annealing chamber 3 there isarranged a guide roll I! which is preferably driven and the diameter ofwhich depends on the thickness of the work to be annealed. At the inletend of the muile a narrow alit l tFigure sl is provided tor the a whilea preferred of the inven entry d exit of the work to be annealed. tionhas been disclosed in the present specifica- The band to be annealedwhich is. unwound iron: the reel 0 passes through the feeding ap-''paratus I and enters the annealing muille 2 through the slit'l. Itpasses over and around the guide roll I! and returns to the inlet of theannealing muille 2 and thence to the winding reel ll. Owing tothegradual increase in height of the annealing chamber at the closed end ofthe furnace I and the large diameter of the roll ii, the returningportion of the band does not come into contact in the enlarged portionof the annealing chamber with the entering portion of the band thusallowing free circulation of gases so that an intense heating of bothparts of the band is'ensured. After leaving the annealing chamber 3 thereturning band approaches nearer to the entering band. Scratching of thebands owing to their sliding one over the other need not a into theannealing chamber can be dispensed with if the work entering the furnaceis wetted with oil or oil is dropped on to itor coal dust, siliconcarbide, naphthalene or anthracene resi: dues are introduced intothe-furnace.

be feared along as no dirt enters between the masses tion, it will beunderstood thatfalteratlons and modifications of various 'kinds maybe'made therein without departing from the spirit of the invention, thatis, the present specification is to be considered in an illustrative andnot in a limiting sense. The scopeofthe invention-is defined solely bythe following claim. Y

Y A horizontal furnace for the continuous annealing of a continuouslength of flexible material. said furnace havinga relatively long sub--stantially horizontal preliminary heat exchange portion which isvertically narrow, said portion having a single openingat one end toreceive and discharge the material. a relatively short heating muilie,means for heating the mums, said muiiie being closed at one'end andopening into the heat exchange portion stiltsother end, a

roll rotatably mounted within the muflle adiacent its closed end, toreceive the material under treatment and reverse its travel, and meansfor feeding the material through said heat exchange portion and throughsaid muiiie, said means in-.

cluding a device for rotating said roll, the ingoing and outgoing runsof said material being maintained at a relatively small spacing from oneanother while traversing said heat exchange portion, by reason of'itsvertical narrowness. v

